PYDay5- 数据类型set、三元运算、函数
1、set
set集合，是一个无序且不重复的元素集合
class set(object): """ set() -> new empty set object set(iterable) -> new set object Build an unordered collection of unique elements. """ def add(self, *args, **kwargs): # real signature unknown """ Add an element to a set，添加元素 This has no effect if the element is already present. """ pass def clear(self, *args, **kwargs): # real signature unknown """ Remove all elements from this set. 清除内容""" pass def copy(self, *args, **kwargs): # real signature unknown """ Return a shallow copy of a set. 浅拷贝 """ pass def difference(self, *args, **kwargs): # real signature unknown """ Return the difference of two or more sets as a new set. A中存在，B中不存在 (i.e. all elements that are in this set but not the others.) """ pass def difference_update(self, *args, **kwargs): # real signature unknown """ Remove all elements of another set from this set. 从当前集合中删除和B中相同的元素""" pass def discard(self, *args, **kwargs): # real signature unknown """ Remove an element from a set if it is a member. If the element is not a member, do nothing. 移除指定元素，不存在不保错 """ pass def intersection(self, *args, **kwargs): # real signature unknown """ Return the intersection of two sets as a new set. 交集 (i.e. all elements that are in both sets.) """ pass def intersection_update(self, *args, **kwargs): # real signature unknown """ Update a set with the intersection of itself and another. 取交集并更更新到A中 """ pass def isdisjoint(self, *args, **kwargs): # real signature unknown """ Return True if two sets have a null intersection. 如果没有交集，返回True，否则返回False""" pass def issubset(self, *args, **kwargs): # real signature unknown """ Report whether another set contains this set. 是否是子序列""" pass def issuperset(self, *args, **kwargs): # real signature unknown """ Report whether this set contains another set. 是否是父序列""" pass def pop(self, *args, **kwargs): # real signature unknown """ Remove and return an arbitrary set element. Raises KeyError if the set is empty. 移除元素 """ pass def remove(self, *args, **kwargs): # real signature unknown """ Remove an element from a set; it must be a member. If the element is not a member, raise a KeyError. 移除指定元素，不存在保错 """ pass def symmetric_difference(self, *args, **kwargs): # real signature unknown """ Return the symmetric difference of two sets as a new set. 对称差集 (i.e. all elements that are in exactly one of the sets.) """ pass def symmetric_difference_update(self, *args, **kwargs): # real signature unknown """ Update a set with the symmetric difference of itself and another. 对称差集，并更新到a中 """ pass def union(self, *args, **kwargs): # real signature unknown """ Return the union of sets as a new set. 并集 (i.e. all elements that are in either set.) """ pass def update(self, *args, **kwargs): # real signature unknown """ Update a set with the union of itself and others. 更新 """ pass
#!/usr/bin/env python # -*- coding:utf-8 -*- # se = {11,22,33,44} # se.add(55) # print(se) # se.discard(66) # #se.remove(66) # print(se) # bf = {21,22,23,25} # # #取se bf的交集 # ret1 = se.intersection(bf) # #取交集并更新se # se.intersection_update(bf) # # print(ret1) # print(se) # # ret2 = se.issubset(bf) # ret3 = se.issuperset(bf) # print(ret2) # print(ret3) # # bf.pop() # print(bf) se = {11,22,33,44} be = {11,22,77,55} r1 = se.difference(be) r2 = be.difference(se) print(r1) print(r2) ret = se.symmetric_difference(be) print(ret) # se.symmetric_difference_update(be) # print(se) ret = se.union(be) print(ret) print(se) se.update([21]) print(se)
1.1习题：
old_dict = { "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }, "#2":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }}new_dict = { "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 800 }, "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } "#4":{ 'hostname':c2, 'cpu_count': 2, 'mem_capicity': 80 }}#老字典key 相同的键值，将新字典key值更新到old，
#老字典中存在，新字典不存在的 将old中的值删除
目的：更新数据源
#!/usr/bin/env python # -*- coding:utf-8 -*- old_dict = { "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }, "#2":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } } new_dict = { "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 800 }, "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 } "#4":{ 'hostname':c2, 'cpu_count': 2, 'mem_capicity': 80 } } old_keys = old_dict.keys() new_keys = new_dict.keys() old_set = set(old_keys) new_set = set (new_keys) del_set = old_set.difference(new_set) add_set = new_set.difference(old_set) update_set = old_set.intersection(new_set)
2、深浅拷贝
2.1 数字和字符串：深浅拷贝、赋值地址都是一样的
2.2 其他（列表、字典、元组）：潜拷贝，只copy 第一层；深拷贝，除底层外 其他都拷贝
3、三目运算也叫三元运算：
eg： name = "Lee" if 1 == 1 else "Alice"
4、字符串
字符串：本质上是c语言的字符数组，不可修改，不可插入。
list：相当于c语言的链表，记录上下元素的位置
5、函数
功能模块，程序调用时直接使用函数名来调用，不用每次都写，实现程序的解耦，提高程序代码效率。
5.1 定义格式
def 函数名（形参）
函数体
5.2 调用格式
函数名（实参）
5.3函数的注意事项：
5.3.1 函数返回值关键字为return，执行return后，函数跳出，不在执行后面的代码；没有return关键字，函数默认返回值None
5.3.2 函数调用时不加参数则按照顺利将实参赋值给函数形参，如需不按顺序传递参数，则在调用时采用“形参=实参”的形式实现
5.3.3 动态参数： * 表示元组，**表示字典，eg：def f（*args,**kwargs）
5.3.4 函数调用时f（li）：将li作为整体传递给函数，f（*li）：将li的元素一个一个的传递给函数
5.3.5 函数体修改全局变量，要使用关键字global
5.4内置函数：
#!/usr/bin/env python # -*- coding:utf-8 -*- def email(): import smtplib from email.mime.text import MIMEText from email.utils import formataddr ret = True try: msg = MIMEText('邮件内容 test mail 2017-1-27 09:16:14 2017年1月27日11:16:37 \n 2017年1月28日06:47:51', 'plain', 'utf-8') msg['From'] = formataddr(["john li", 'lynctest02@tasly.com']) msg['To'] = formataddr(["hi hi ", 'lynctest01@tasly.com']) msg['Subject'] = "主题2017年1月28日06:47:25" server = smtplib.SMTP("mail.tasly.com", 25) server.login("lynctest02", "邮箱密码") server.sendmail('lynctest02@tasly.com', ['lynctest01@tasly.com', ], msg.as_string()) server.quit() except: ret = False return ret i1 = email() print(i1)
6、全局变量与局部变量
局部变量：小写，仅在代码块内生效
全局变量：大写，可以被函数修改，若需修改全局变量加关键字global
7、 try except
try：
c1
except：
c2
#若c1执行错误，则执行c2
8、作业：
1、简述普通参数、指定参数、默认参数、动态参数的区别
A：参见5.3
2、写函数，计算传入字符串中【数字】、【字母】、【空格] 以及 【其他】的个数
def f1(arg): al_num = 0 spance_num = 0 digit_num = 0 other_num = 0 for i in arg: if i.isdigit(): digit_num += 1 elif i.isspace(): spance_num += 1 elif i.isalpha(): al_num += 1 else: other_num += 1 return (al_num,spance_num,digit_num,other_num) r = f1("11134 t gfsfgf adf adfa dasf**") print(r)
3、写函数，判断用户传入的对象（字符串、列表、元组）长度是否大于5。
def obj_len(arg): #如果是字符串、元组、列表 if isinstance(arg,str) or isinstance(arg,tuple): if len(arg)>5: return True else: return False else: return None temp = {1:1,2:1} ret = obj_len(temp) print(ret)
4、写函数，检查用户传入的对象（字符串、列表、元组）的每一个元素是否含有空内容。
def has_space(args): ret = True for c in args: if c.isspace(): ret =False break return ret result = has_space("1123asdfdf") print(result)
5、写函数，检查传入列表的长度，如果大于2，那么仅保留前两个长度的内容，并将新内容返回给调用者。
def f2(args): if len(args)>2: return args[0:2] else: return args li = [12,34,56] print(f2(li))
6、写函数，检查获取传入列表或元组对象的所有奇数位索引对应的元素，并将其作为新列表返回给调用者。
def f4(arg): ret = [] for i in range(len(arg)-1): if i % 2 == 1: ret.append(arg[i]) else: pass return ret li = [11,22,33,44,55] r = f4(li) print(li) print(r)
7、写函数，检查传入字典的每一个value的长度,如果大于2，那么仅保留前两个长度的内容，并将新内容返回给调用者。
dic = {"k1": "v1v1", "k2": [11,22,33,44]}PS:字典中的value只能是字符串或列表
def f5(arg): ret ={} for k,v in arg.items(): if len(v) > 2: ret[k] = v[0:2] else: ret[k] = v return ret dic = {"k1": "v1v1", "k2": [11, 22, 33, 44],"k3":"12"} r = f5(dic) print(r)
def f6(arg): for k,v in arg.items(): if len(v) > 2: arg[k] = v[0:2] else: arg[k] = v dic = {"k1": "v1v1", "k2": [11, 22, 33, 44],"k3":"12"} f6(dic) print(dic)
